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Browsing Theses and Dissertations by Subject "Angus cattle"

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    Angus cattle at high altitude: pulmonary arterial pressure, estimated breeding value and genome-wide association study
    (Colorado State University. Libraries, 2016) Zeng, Xi, author; Thomas, Milton G., advisor; Enns, R. Mark, advisor; Speidel, Scott E., committee member; Holt, Timothy N., committee member
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    Pulmonary arterial pressure in Angus cattle: environmental influences and relationship with growth and carcass traits
    (Colorado State University. Libraries, 2017) Pauling, Rachel, author; Enns, R. Mark, advisor; Holt, Timothy N., committee member; Speidel, Scott E., committee member; Thomas, Milton G., committee member
    Right-side heart failure (RHF) resulting from hypoxia induced pulmonary hypertension is most commonly observed in cattle located at high elevations, but has been observed in some feedlot cattle residing at low elevations as well. Beef cattle producers typically use pulmonary arterial pressure (PAP) observations to predict an animal's susceptibility to RHF. The objective of this this study was to investigate the effect of elevation on PAP measures, and to evaluate the relationship between PAP, growth traits, and carcass traits in Angus cattle. The first study utilized PAP and elevation data obtained from the American Angus Association (AAA, n = 4,511), Colorado State University Beef Improvement Center (n = 5,433), and Dr. Timothy Holt DVM (n = 4,821). A univariate analysis of PAP as used to obtain elevation solutions to be input to a polynomial regression to determine high versus low elevation (1,620 m). Then a bi-variate analysis was performed to evaluate the genetic relationship between PAP observations obtained at high elevations as well as low elevations. Results from this study indicate that PAP observations obtained at any elevation can be considered the same trait with a genetic correlation of (0.83 ± 0.15). The second study utilized data obtained from AAA (n = 4,509) which included PAP, growth, and carcass traits. Multivariate analyses of PAP and growth traits, as well as PAP and carcass ultrasound traits were used to obtain estimates of heritability and genetic correlations. Results from these analyses indicated that there are moderate genetic correlations between PAP and maternal birth weight (0.55 ± 0.12) as well as PAP and ultrasound ribeye area (0.24 ± 0.12). These results suggested that selection for increased growth and muscling in cattle could consequently increase PAP observations.